1. Field of the Invention
The present invention relates to a method of producing a solid body having a depressed portion on a surface. More specifically, the present invention relates to a method of producing a solid body having a surface formed with a depressed portion by self assembly from selection of a specific solution composition.
2. Description of the Related Art
Recently, in a variety of fields the shape of solid body surfaces is attracting attention and being researched. For example, Japanese Patent Application Laid-Open No. H01-268733 discloses a method of producing a porous membrane having uses in a filter or the like by condensation fine droplets on a substrate, coating the substrate with a membrane material solution that is immiscible with the fine droplets and drying the thus-formed substrate. Japanese Patent Application Laid-Open No. H08-311231 discloses a method of producing a porous body having a honeycomb structure by coating a cooled polymer solution to condense vapor in the atmosphere on the coated surface. If a plating film is formed on an underlayer having such a surface shape, the anchor effect of the plating film is increased, whereby the plating film adhesion is improved. Japanese Patent Laid-Open Nos. 2001-157574 and 2002-335949 disclose a method of producing a porous body having a honeycomb structure by casting a hydrophobic organic solvent solution of a biodegradable, amphiphilic polymer to condense droplets on the cast solution surface. This porous body is expected to be used in applications in the medical field.
However, with the method disclosed in Japanese Patent Application Laid-Open No. H01-268733, not only does the process become more complicated because a membrane material solution has to be coated after the fine droplets have been condensed on the substrate, but the choice of materials is restricted because the membrane material solution has to be immiscible with the fine droplets. Further, with the method disclosed in Japanese Patent Application Laid-Open No. H08-311231, because a polymer solution has to be cooled, not only is there a risk of coating defects occurring as a result of water mixing into the polymer solution, but countermeasures have to be taken against dew forming in the pipes or the like, and production equipment, such as a cooling apparatus or the like, has to be provided. In addition, with the methods disclosed in Japanese Patent Application Laid-Open Nos. 2001-157574 and 2002-335949, in order for the droplets to condense on the surface, a special amphiphilic polymer is required and the surrounding environment has to be controlled, so that in the case of blowing a high-humidity gas or air, there are the drawbacks that the surface of the cast film may become disorderly, and that the production conditions are equipment are more restricted.